The present invention relates to improvements in provisions for dissipating heat from miniature electrical packages of components or devices, and, in one particular aspect, to novel and advantageous stamped-metal heat sinks of economical construction which readily accept and securely attach themselves in efficient heat-exchange relationship to modules of the dual-in-line package type, with improved release of unwanted thermal energy to ambient environment being effected by a broad-area radiating member held in favorably-spaced relation to the package by integral spring-clip members uniquely arranged to flex into intimate engagements with opposed surfaces of the package and which separately and without interference with one another conduct heat from those surfaces to the main radiating member. Unbalanced resiliencies exhibited by the spring-clip members, which can impair their flexing into optimum abutments with the package surfaces once they have been forcibly wedged apart by insertion of the package, are offset by stiffening indentations of the stamped metal at flexure sites where yielding tendencies are excessive, and the same indentations are preferably disposed to aid in spacings which thermally isolate package end surfaces and promote maximum cooling.
Miniature electrical and electronic units, such as those in which devices or components or circuits are packaged in molded modular form for automated interconnections in printed-circuit board environments, commonly have power-handling limitations which are largely determined by their abilities to expel internally-generated heat and thereby avoid general or localized thermal degradations or failures within them. Performance of such units can often be very significantly extended or enlarged with the aid of finned metal extrusions or stampings which will conduct and radiate heat away from thermally-vulnerable regions, thereby upgrading relatively low-cost items into more demanding and valuable service than their uncooled ratings would otherwise allow. Some units, and notably those of the dual-in-line package (DIP) type, have both upper and lower broad-area surfaces from which heat should best be extracted efficiently if the units are to operate safely nearer theoretical peaks of performance. It has been known to form the cover of the sealed enclosure of a semiconductor package as an integral heat-radiating member, and to enhance the flow of heat from at least the top of the package by way of a pillow in which a thermally-conductive material is contained by a film (U.S. Pat. No. 4,092,697). And, in situations where the package is to be cooled with the aid of accessory heat-sink attachments, it has been proposed that a winged sheet-metal radiator be held on top of an integrated-circuit package by pairs of fingers struck from the same metal and disposed to grasp edges of the package; more secure fastening has also been available through soldering of special tabs and fingers of the mated items (U.S. Pat. No. 3,670,215). Along the latter lines, it has also been a practice to bond light-weight heat-radiators directly to the top of a package, using an adhesive which conducts well. More conveniently, however, and offering more efficient broad-area contacting as well, a small sheet-metal heat-sink is fashioned either as a one-part or two-part spring clip which fits not only along the top of an elongated package but also fully along the bottom, where commonly the greater heat build-up tends to occur and yet where there is little space available between the bottom of the package and the confronting top surface of a printed-circuit board on which the package is mounted. My joint U.S. Pat. Nos 4,203,488 and 4,235,285 disclose such clip-type heat sinks. In some instances, mechanical locking of a spring-clip heat sink may be adequately provided with the aid of detenting, such as is described in connection with the tab-engaging units in U.S. Pat. Nos. 3,893,161 and 4,012,769; in other cases, the clasp end of a clip unit such as is featured in my said U.S. Pat. No. 4,235,285 may simply be omitted and the unit permitted to yieldably clamp itself in place.
As appears more fully hereinafter, a unique and advantageous arrangement for withdrawing and dissipating excess thermal energy from small electronic packages or modules includes a self-fastenting clip unit in which two heat-conducting elements engage opposite surfaces of such a package and independently conduct heat away from it to a third integral element which effects an efficient release of such heat to the surrounding or ambient atmosphere. That folded-back arrangement of elements bears some superficial resemblance to a prior resilient accessory clip used to press a separate fingered heat-dissipation member into intimate contact with a component which is to be cooled (U.S. Pat. No. 3,548,927), but it will be appreciated that the clip there is not itself a primary heat-dissipating device and it functions instead as a mere resilient clamp for a component and dissipator.